Please don't wait too long man. I am coming into the 3rd week of flowering myself and my plants have grown so damn much. I should have started flowering a month and a half ago at least. My plants were 3 feet two weeks ago and today they are a bit over four and a half and a few ovver five feet. I am going to have to add more light, make a special light hanger, and even tie the plants so they take less horizontal room up. If you're not prepared to expand, or to go to such extreme measures, then please don't wait to flower. I know you want the most bud you can get, but if your plant gets too big and you can't do anything then you will have wasted a lot of money and time.